<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="timer"> </div>
    <button> 停止</button>
</body>
<script>
    //在页面生成动态时钟 2021-10-19 11:48:30
    // setInterval
    function  sj(){
    var  date1 = new Date();
    var  year = date1.getFullYear();
    var month = date1.getMonth();
    month =month+1;
    var day = date1.getDate();

    var hour = date1.getHours();
    var minute =date1.getMinutes();
    var sec = date1.getSeconds();
    month =identify(month);
    day = identify(day);
    hour = identify(hour);
    minute = identify(minute);
    sec = identify(sec);
    var result = year +"-"+month+"-"+day+" "+hour+":"+minute+":"+sec;
    return result;
    }
    var timerId =setInterval(function(){
        var result = sj();
        var timer = document.getElementById("timer");
        timer.innerHTML= result;
    },1000)
    var btn = document.getElementById("btn");
    btn.onblick = function(){
        clearInterval(timerId);
    }
</script>
</html>